An anisotropic electrically conductive film, in which electrically conductive particles are dispersed in an electrically insulating resin binder, is widely used when an electronic component such as an IC chip is mounted on a wiring board and the like; however, in such an anisotropic electrically conductive film, it is known that electrically conductive particles are present in a state of being connected or aggregated with one another. Therefore, in a case where the anisotropic electrically conductive film is applied to connect IC chip terminals and wiring board terminals, the pitches of which are reduced as an electronic device is reduced in a weight thereof and miniaturized, a short circuit may occur between the adjacent terminals due to the electrically conductive particles that are present in a state of being connected or aggregated in the anisotropic electrically conductive film.
Conventionally, a film, in which electrically conductive particles are regularly arranged, is suggested as an anisotropic electrically conductive film to deal with such a narrow pitch. For example, an anisotropic electrically conductive film is suggested which is obtained as follows: after an adhesive layer is formed in a stretchable film and the electrically conductive particles are densely packed in a single layer on a surface of the adhesive layer, the film is biaxially stretched until the distance between the conductive particles reaches a predetermined distance to arrange the electrically conductive particles regularly, then the electrically conductive particles are transferred to an electrically insulating adhesive base layer by pressing an electrically insulating adhesive base layer against the electrically conductive particles, the electrically insulating adhesive base layer being an element of the anisotropic electrically conductive film (Patent Document 1). Alternatively, an anisotropic electrically conductive film is also suggested which is obtained as follows: electrically conductive particles are scattered on a transfer-type concave portion formation surface having a concave portion on a surface, the concave portion formation surface is squeegeed and the electrically conductive particles are held in the concave portion, the electrically conductive particles are primarily transferred to the adhesive layer by pressing therefrom an adhesive film on which an adhesive layer for transfer is formed. Next, the electrically conductive particles deposited on the adhesive layer are transferred to an electrically insulating adhesive base layer by pressing the electrically insulating adhesive base layer against the electrically conductive particles being deposited to the adhesive layer, the electrically insulating adhesive base layer being an element of the anisotropic electrically conductive film (Patent Document 2). In general, in these anisotropic electrically conductive films, an electrically insulating adhesive cover layer is laminated on the surface of the electrically conductive particle side to cover the electrically conductive particles.